The present invention relates to fuel pumps and more particularly to fuel pumps which reduce the possible accumulation and effects of contamination on the impellers.
Conventional tank-mounted automotive fuel pumps typically have a rotary pumping mechanism positioned within a housing. Fuel flows into a pumping chamber within the pump housing, and a rotary pumping element (e. g. impeller) causes the fuel to exit the housing at a high pressure. Regenerative fuel pumps are commonly used to pump fuel to automotive engines because they have a higher and more constant discharge pressure than, for example, positive displacement pumps. In addition, regenerative pumps typically cost less and generate less audible noise during operation.
In regenerative pumps of this type, fluid, such as gasoline, is pressurized and supplied by an impeller through the housing where the fluid cools the motor and is eventually-supplied to the vehicle engine. The impeller is positioned in a cavity or chamber formed between an end cap and pump cover on the pump housing. An inlet port is situated on the end cap for introducing the fluid into the impeller chamber. The pump cover on the housing has a discharge port in which fuel pressurized by the impeller is discharged into the pump housing. Mating C-shaped grooves in the inner surfaces of the end cap and pump cover help direct fuel from the inlet port, around and through the impeller, and out the discharge port.
The impeller typically has a plurality of vanes around its perimeter which are used to pressurize the fuel in the impeller cavity and force it into the pump housing. The impeller also can have an outer ring around the perimeter of the vanes and adjacent a wall of the impeller cavity. Often, contamination from dust, sand and the like causes wear and roughening of the outer ring of the impeller, as well as on certain areas in the flow passageways and chambers in the end cap and pump cover. This can result in pumping losses, higher motor torque (thus higher current usage) and decreased pump efficiency.
The present invention provides an improved fuel pump for supplying fuel to a vehicle engine from a fuel tank. The fuel pump includes a pump housing, a motor mounted within the housing and having a shaft extending therefrom, and an impeller mounted on the shaft for rotation therewith. The impeller is positioned in a cavity or chamber between a pump cover member connected to the pump housing and an end cap member. The impeller has a plurality of openings and radially outwardly extending vanes around its outer circumference and an outer ring attached to the outer end of the vanes.
The end cap member has an inlet port which directs fuel into the impeller chamber, while the pump cover member has an outlet port which discharges pressurized fuel from the impeller chamber into the pump housing. Fuel entering the pump housing passes by the motor and is directed to the vehicle engine.
A C-shaped groove or channel on the impeller chamber side of the end cap member communicates at one end with the inlet port. A mating C-shaped groove or channel on the impeller chamber side of the pump cover communicates at one end with the outlet port.
The outer surface of the impeller ring has a non-uniform configuration in order to reduce the contact surface of the impeller outer ring with the stationary pump components. The outer surface can be angled, rounded, scalloped, grooved or the like.
The outlet port on the pump housing cover has an enlarged opening (or xe2x80x9cwindowxe2x80x9d) which reduces fuel restriction and increases the flow of fuel into the fuel pump. The larger passageway in turns helps wash out or push out any contaminants which could cause wear on the impeller, end cap and pump cover components.
The downstream end of the C-shaped groove in the end cap member is enlarged and angled radially outwardly in order to generate increased fuel flow through and past the impeller. This also decreases the opportunity for contamination to affect the vanes and outer surface of the impeller, and helps flush out any contamination which may have been deposited or built-up.
It is, therefore, an object of the present invention to provide an improved fuel pump mechanism with a ringed impeller which reduces potential contamination and its effects in and around the impeller and impeller chamber. It is another object of the present invention to change the speed and flow paths of contamination in the fuel pump and to guide and flow it out more easily from the impeller chamber in order to have less impact on the fuel pump components.